I've been riding my FX around with a Gerbing Heated vest and Koso Apollo heated grips. Together, they consume 105 watts from the DC-DC converter, and this seems to be fine.
For the Gerbing (RIP), I got an SAE to coax adapter and plugged it into the stock SAE connector. The coax just hangs out of the side of the bike and can be tucked into the fairing when not in use.
For the heated grips, I mated a Sumitomo to the grip controller and plugged it into the stock Sumitomo connector (instructions in another post).